1. Field of the Invention
The present invention relates generally to a routing method to be used in a connection-oriented packet network. It particularly relates to a transaction-based routing method that applies particular routing procedures wherein one example uses Global Title Translation (xe2x80x9cGTTxe2x80x9d) techniques for query and response messaging in an ATM network.
2. Background Art
In communication networks (e.g., telecommunication, packet data, etc), addressing and routing are important network functions enabling efficient communication connectivity. Particularly, for the telecommunication network, addressing and routing are typically performed using Global Title Translation (xe2x80x9cGTTxe2x80x9d) as described in Signaling System 7 (xe2x80x9cSS7xe2x80x9d), the out-of-band network control signaling system first standardized by the CCITT (now xe2x80x9cITU-Txe2x80x9d) in 1980. SS7 itself is a connection-less packet network and provides network control signaling for a telecommunications switching network, a circuit-switched network.
Specifically, GTT is a part of the SS7 sub-protocol (i.e., layer), signaling connection control part (xe2x80x9cSCCPxe2x80x9d). Transaction capabilities application part (xe2x80x9cTCAPxe2x80x9d) uses the signaling connection control part (xe2x80x9cSCCPxe2x80x9d) for the transfer of non-circuit related information between signaling-points in the system, particularly transaction-based information exchange between network entities enabling enhanced services in the telecommunications network. Examples of these services include enhanced dial-1-800 service, automated credit card calling, and virtual private networking. The TCAP protocol enables these services to access remote databases such as service control points (xe2x80x9cSCPsxe2x80x9d) to complete call processing. An SCP can supply the translation and routing information necessary for delivering advanced network services such as translating dialed digits (e.g., 1-800 number) to the required routing number (e.g., routing telephone number). In particular, GTT, performed by signal transfer points (xe2x80x9cSTPxe2x80x9d), comprises the process of translating a global title address of dialed digits to a point code (network code) address and application address (subsystem number) enabling call connectivity within the telecommunications network.
A connection-oriented packet network provides data transport by performing call requests to set up logical connections between communication nodes within the network. The network typically includes a plurality of nodes, devices that communicate with other devices in a communications network. The logical connections are referred to as virtual circuits or connections (VCs). Virtual circuits are connection-oriented channels typically established between two end nodes in a packet network. Switched virtual circuits (SVC) are dynamically established using call setup procedures and terminated once the data transfer has been completed. All packets transported within the network are identified as belonging to a particular virtual circuit wherein the packets are numbered sequentially and delivered in sequence-number order. Connection-oriented networks enable connection-oriented services that include sequencing, error control, file transfer, and remote terminal access. Conversely, in a connectionless network, the network delivers packets independently of each other which may result in non-sequential and unreliable delivery.
Particularly, an asynchronous transfer mode (xe2x80x9cATMxe2x80x9d) network is a connection-oriented packet network wherein data is routed over virtual circuits by switching/routing devices referred to as ATM switches. ATM switches allow VCs to be set up and torn down on demand by an end user.
In a typical ATM network, due to the frequency of data transport, permanent virtual circuits (PVCs) will be setup between connecting communication nodes. A permanent virtual circuit is a permanent, network-assigned virtual circuit. It typically provides the equivalent of a dedicated private line service over a packet network between nodes. Data transfer occurs as with SVCs, but no call setup or termination is required. A soft PVC is a PVC that is setup via signaling between all nodes involved in the circuit. The signaling is triggered through commands entered at one of the end nodes of the circuit, either directly or through an operations system. Once established, a soft PVC operates identically to a PVC. Particular ATM terminology refers to a PVC as a virtual channel (xe2x80x9cVCxe2x80x9d) or virtual path (xe2x80x9cVPxe2x80x9d) PVC. A virtual path PVC is also known as permanent virtual paths (xe2x80x9cPVPxe2x80x9d). A PVP is a set of connection-oriented channels between two end nodes in a packet network. A PVP is a virtual path that provides the equivalent of a set of dedicated private line services over a packet network. FIG. 1 shows the relationship between the physical circuit and the logical virtual path (VP) and virtual channel (VC) connections in an ATM network. Once defined, a PVP requires no setup operation before data is sent and no disconnect operation after data is sent. Other examples of connection-oriented packet networks include X.25 and Frame Relay.
A typical routing topology within an ATM network includes a plurality of interconnected communication nodes that provide end-to-end communication services. These interconnected nodes are commonly a combination of edge nodes and intermediate nodes. Edge nodes typically are connected to end systems (xe2x80x9cESxe2x80x9d). End systems typically comprise end-user customer premises equipment (xe2x80x9cCPExe2x80x9d). Intermediate nodes are connected to edge nodes as well as other intermediate nodes. Commonly, the interconnected communication nodes of the ATM network can be any combination of switches, databases, directory servers, or other ATM devices. FIG. 2 shows a representative example of the nodal interconnections within an ATM network providing end-to-end service connectivity.
In a specific application, switch nodes query database nodes within the network during a transaction. This database transaction comprises a query message and its corresponding response message communicated between the switch and the database. Databases are nodes that typically contain network and customer information which can be queried by other nodes in the communications network. Commonly, the query messages and response messages from the databases are sent over PVCs that are established between every switch and database within the network. In a network of 300 switches and 150 databases, 45,000 PVCs are therein required to establish complete connectivity in the network. The outlaying of these connections greatly increases network management costs as well as creating traffic control and distribution problems.
There is a need to simplify PVC provisioning within an ATM network particularly for transaction-based routing. There is also a need to effectively and efficiently route transaction-based messages within the network without requiring a fault-tolerant directory server to provide intermediate node connectivity.
The present invention overcomes the previously mentioned disadvantages by providing an intermediate node that applies particular routing procedures including GTT techniques to effectively route data messages and response messages within a connection-oriented packet network. The intermediate node advantageously comprises a non fault-tolerant directory server that is connected via permanent virtual circuits to switch and database edge nodes for query and response messaging within an ATM network. Based on information in the received message, the intermediate node translates the destination address to a network routable address and determines an appropriate network routing path to effectively route the transaction-based message to the intended destination node.